Since Apple Computer Corporation introduced the mouse in 1984, it has become an indispensable input device to control personal computers. It is called mouse mainly because of its shape and wire.
The general mouse has a track ball which has a portion exposed outside. When the track ball is rolled by force, two circular disks located in the mouse normal to each other will be turned with the track ball. Meanwhile, through optical detection, the turning speed of the two circular disks will be transformed to a moving distance on the perpendicular coordinates. Hence on the electronic equipment connected to the mouse, a cursor on the screen will be moved from an initial position to an objective position. For such a mouse, the force being applied to move the mouse is through the wrist of a user's hand. Operation in such a way for a long period of time could cause ache and injure the wrist.
In order to satisfy users' working types and their computer habits, there are constant innovations and improvements on the design of the mouse, and a wide variety of mice has been developed and introduced. They have different features and different functions.
Often, a mouse adopts an optical structure or a mechanical structure with the track ball on the bottom of the mouse body. Another design places the track ball on an upper side of the mouse body newly, so that the track ball may be rolled by fingers to move the cursor or provide other functions. Thus the design resolves the problem of desktop space constraint during mouse movement, and the problem of preventing dust on the desktop from being carried into the mouse. However, the track ball still has to be rolled by fingers continuously for moving the cursor from the initial position to the objective position. Although they are more convenient to use, they still could cause ache or injury to user's fingers when used for a long period of time.
Moreover, the technique of using a joystick to control the cursor has been developed later. Pushing the joystick can control and move the cursor to the objective position without continuously rolling the track ball. But when the joystick is pushed and released, it returns to the center position and gives the finger pressure. The further away it is being pushed, the greater the pressure it exerts on the finger. This also hurts the finger when used for a long period of time.